Generally, a smartkey system is a system that is built into a vehicle, and when a driver makes a desired action in a state of holding a smartkey, senses the action to control driving of the vehicle. The smartkey system includes a remote keyless (RKE) system and a passive keyless (PKE) system.
The PKE system is a system that remotely locks/unlocks a door of a vehicle even without holding a vehicle key. The PKE system is a system in which a driver or an owner of a vehicle locks/unlocks a door of the vehicle and starts the vehicle in a wireless manner at a position near the vehicle. Here, the smartkey is generally called a fob key, and is simply called a fob.
The vehicle smartkey system includes: a plurality of low frequency (LF) antennas that cover, as a communicable area, an indoor area of a vehicle and an outdoor area around the vehicle; a radio frequency (RF) antenna that receives an RF signal from a smartkey; and a smartkey electronic control unit (SMK ECU).
FIG. 1 is an exemplary diagram of a related art vehicle smartkey system. An SMK ECU of the vehicle smartkey system enters a warning mode after doors of a vehicle are locked. When a driver moves from the vehicle by a certain distance with the driver holding a fob, the SMK ECU switches a current vehicle mode to a sleep mode, folds side mirrors of the vehicle, and periodically starts WelcomeSearch. For the WelcomeSearch, the SMK ECU wakes up, and periodically (for example, at intervals of 240 ms) transmits wakeup data having a low frequency through an antenna that is attached to a driver door or an assistant door. The fob near the vehicle receives the transmitted wakeup data, and compares the wakeup data with data that is previously learned and stored. When it is determined that the wakeup data matches the learned data, the fob transmits RF data to the SMK ECU. The SMK ECU compares the RF data with the learned data, and when it is determined that the RF data matches the learned data, the SMK ECU releases the sleep mode of the vehicle smartkey system, turns on a puddle lamp, and folds the side mirrors.
The WelcomeSearch of the related art is performed in the sleep mode of the SMK ECU. As illustrated in FIG. 2, the SMK ECU wakes up at every interval of 240 ms, and performs the WelcomeSearch and PKE search. When there is no received data, the SMK ECU is again switched to the sleep mode. In performing the WelcomeSearch, when the fob responds or RKE data is received from the fob, the SMK ECU releases the sleep mode of the vehicle smartkey system, and simultaneously performs a requested operation.
In the existing method, the SMK ECU transmits an LF request, and when there are two fobs, in order for a malfunction not to be caused by data interference between the two fobs, the SMK ECU stands by for receiving all of RF data in a state where a section is divided into a plurality of sections. In providing an RF data response, each of the two fobs transmits the RF data in only its own section.
Subsequently, the SMK ECU determines whether the RF data received through an RF antenna matches a pre-stored identification number of the vehicle. When it is determined that the RF data matches the pre-stored identification number, the SMK ECU determines there to be a fob which has been found through the WelcomeSearch, and performs operations such as an operation of turning on the puddle lamp, an operation of unfolding the side mirrors, etc.
In the related art smartkey system, since the SMK ECU or an RF receiver periodically wakes up in the sleep mode, the WelcomeSearch needs a long time of a minimum of about 94 ms after LF data is transmitted, and considering noise and an RF tolerance, a time necessary for the WelcomeSearch more increases. Therefore, a dark current is greatly consumed, and an operation time is extended by reception standby that is performed due to an additional fob. Therefore, the dark current increases in proportion to the extended operation time. Also, considering the dark current or a time margin in a whole sleep mode, there is a limitation in task arrangement even in a case of applying new technology in which the SMK ECU operates in the sleep mode.